Considerable effort has been expended during the past decade on the development of materials suitable for use as cardiovascular, artificial kidney, and various other implant sites. Despite some promising results for certain materials in vivo as illustrated through the absence of thrombus formation, repeated experiments lack consistency without any materials or methods for developement of a material emerging. A synthetic route for making an inherently nonthrombogenic polymer is years from any practical applications. Surface modification through the use of heparin or other agents may prevent coagulation, however a thin layer of platelets is always observed on the surface that may cause subsequent thrombus formation. This proposal is directed toward a simple and systematic approach to the development of nonthrombogenic surfaces using presently available materials and evaluating the new systems in experimental animals. Biologically active agents will be combined with polymers and are capable of stimulating intracellular levels of cyclic adenosine monophosphate (cAMP). Slow release of the agents affect platelet function at the interface preventing platelet adhesion and interfacial induced thrombosis. The rational of the proposal is based on interfacial biochemistry, pharmacological effects on platelet function, and preliminary data supporting the proposed methods. The in vitro and in vivo experiments proposed will provide polymers with surfaces capable of not forming initial thrombus formation in cardiovascular and other surgical implants.